JP2002296126A - Torque detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque detector being from mechanical contacts, and hence excellent in reliability, and free from detection errors due to assembly. SOLUTION: The torque detector 10 is a device which measures a torque acting on a torsion bar 18. The torsion bar 18 has two supporting parts 26 fixed spaced-apart in the direction of its long axis (central axis 11). A distortion wire 27 has an electric wire part 27a stretched between the two supporting parts 26. An electric source device 29 applies a predetermined voltage to the distortion wire 27. At this time, a current passing through the wire 27 is detected with a current detector 31. The current value detected with the current detector 31 is used for calculation of torque acting on the torsion bar 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a torque acting on a rod.

[0002]

2. Description of the Related Art As shown in FIG. 1, in EPS (Electronic Control Power Steering) control of a vehicle, a torque input from a steering wheel 1 is detected by a torque detecting device 2, and the detected signal is measured by a vehicle speed sensor 3. The control unit 4 performs arithmetic processing on the vehicle speed signal and transmits a control signal to the motor 5. The motor 5 is driven based on the control signal to power assist the steering. On the other hand, the rotation of the motor 5 is detected by the rotation sensor 6, and the motor 5 is feedback-controlled by the detection signal. Motor 5
The rotational force assisted by the gearbox 7
And the direction of the tire 8 is changed. Thus, the torque detecting device 2 plays an important role in detecting the torque applied to the steering wheel 1 in the EPS control.

A device for detecting a torque acting on a rod-like body such as a torsion bar is disclosed in
There is one described in 206422. This torque detecting device includes an input shaft and an output shaft coaxially connected via a torsion bar. The input shaft has an electric resistance portion fixed around the input shaft. On the other hand, the output shaft has a conductive brush when it contacts the electrical resistance part. The contact position between the conductive brush and the electric resistance unit changes according to the torque transmitted from the input shaft to the output shaft. Then, the change in the contact position is taken out to the outside as a voltage change, and the torque is detected based on the voltage change.

[0004]

However, since this torque detecting device is configured to detect the torque based on the mechanical contact between the electric resistance portion and the conductive brush, the electric connection portion and the conductive brush are not detected. Wears the contact area.
Then, this wear causes a decrease in durability and reliability of the torque detecting device. Further, it is necessary to adjust the initial contact position and the contact pressure between the conductive brush and the electric resistance portion, and the adjustment error appears as a detection error.

[0005] Therefore, the present invention has no mechanical contact,
It is therefore an object of the present invention to provide a torque detecting device which is excellent in durability and reliability and has no detection error caused by assembly.

[0006]

According to a first aspect of the present invention, there is provided a torque detecting device for measuring a torque acting on a rod-like body. And two support portions fixed to the rod-shaped body at a distance in the longitudinal direction thereof, and an electric wire portion stretched between the two support portions, and the strain and the electric resistance have a predetermined relationship. A strain wire, a power supply device for applying a predetermined voltage to the strain wire, and a current detector for detecting a current flowing through the strain wire.

According to another aspect of the present invention, there is provided a torque detector, a power supply device, two support portions fixed to the rod-shaped member at a distance in a longitudinal direction thereof, and the two support portions. A strain wire having a predetermined relationship between strain and electric resistance, the strain wire having two wire portions stretched between portions and having one wire portion and the other wire portion connected in series to the power supply device; A current detector for detecting a current flowing through the wire.

According to another aspect of the present invention, there is provided a torque detector, a power supply device, two support portions fixed to the rod-shaped member at a distance in a longitudinal direction thereof, and the two support portions. A strain wire having two wire portions stretched between portions and having one wire portion and the other wire portion connected in parallel to the power supply device, and having a predetermined relationship between strain and electrical resistance; A current detector for detecting a current flowing through the wire.

According to another aspect of the present invention, the one or the other electric wire portion connected in series is covered with a magnetic shielding member.

[0010] In another aspect (claim 5) of the present invention, the electric wire portion is stretched in parallel with a long axis of the rod-shaped body.

In another aspect of the present invention, the electric wire portion is stretched non-parallel to the long axis of the rod.

According to another aspect of the present invention, the two electric wires connected in parallel are arranged so as to cross each other around the rod.

According to another aspect of the present invention, the current detector detects a magnitude of the current based on a change in a magnetic field caused by a change in a current flowing through the electric wire. It is a non-contact type current detector.

According to another aspect of the present invention, the non-contact type current detector has an annular ring made of a conductive material, and the annular ring is disposed so as to surround the electric wire portion. It is characterized by having been done.

According to another aspect of the present invention, the non-contact type current detector has an annular ring made of a conductive material, and the annular ring includes the electric wire portion and the rod-shaped body. Are arranged so as to surround the.

According to another aspect of the present invention, the rod is covered with a magnetic shielding member.

According to another aspect of the present invention, the rod-shaped member is provided with an electrical insulator for preventing a current from flowing between the two support portions. And

According to another aspect of the present invention, the power supply device includes a primary coil provided on a fixed portion supporting the rod, and a primary coil provided on the rod and provided with the primary coil. And a secondary coil magnetically connected to the strain wire and an alternating current source for applying an alternating current to the primary coil.

According to another aspect of the present invention, there is provided a torque detecting device comprising an arithmetic circuit for calculating a torque applied to the rod from the output of the current detector.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

[First Embodiment] FIGS. 2 to 4 show a torque detecting device according to a first embodiment. As shown in FIG.
The torque detecting device 10 is a device that detects a torque transmitted from an input shaft 12 coaxially arranged along a central axis 11 to an output shaft 13, and includes a housing 14. The housing 14 has a torque transmission mechanism 15 that outputs torque input from the input shaft 12 to the output shaft 13. The torque transmission mechanism 15 includes two couplings (an input side coupling 16 and an output side coupling 17) and a torsion bar (rod-like body) 18. In this embodiment, the input shaft 12, the output shaft 13, and the torsion bar 18 are used.
Are each constituted by a solid cylinder, but may be a hollow member or a polygonal cross section.

The two couplings 16 and 17 are supported by the housing 14 via bearings 19 and 20 so as to be rotatable about the central axis 11. The input side coupling 16 includes an outer connecting portion 21 and an inner connecting portion 22, and the end of the input shaft 12 and one end of the torsion bar 18 are coaxial through the outer connecting portion 21 and the inner connecting portion 22. Are linked. Similarly, output side coupling 1
7 has an outer connecting portion 23 and an inner connecting portion 24,
The end of the output shaft 13 and the other end of the torsion bar 18 are coaxially connected via the outer connecting portion 23 and the inner connecting portion 24. In the present embodiment, the connecting portion is embodied as a concave portion, but any structure may be used as long as it can transmit the torque of the input shaft 12 to the output shaft 13 via the torsion bar 18. Is also good.

As shown in FIG. 2, the torsion bar 18
Are fixedly supporting two support portions 25 arranged at a predetermined interval in a direction parallel to the central axis 11. In the present embodiment, the two support portions 25 are arranged on the same vertical section passing through the central axis 11 (FIGS. 3A-1 and 3A-1).
2)). Each support portion 25 is located at a position moved a predetermined distance radially outward from the outer peripheral surface of the torsion bar 18,
A through hole 26 extending in a direction parallel to the torsion bar central axis 11 is formed.

The wire (electric wire) 27 is a strained wire having a predetermined relationship between strain and electrical resistance. The strain generated in the wire 27 and the electrical resistance corresponding to the strain are defined by a linear function. The wire 27 is inserted through the through hole 26 and is connected to both poles of a DC power supply (power supply device) 29 in a circuit box 28 held in the housing 14. The through-hole 26 is filled with an adhesive 30 made of an insulating material, and the wire 27 is fixed with a predetermined tension applied to a wire portion 27a supported between the two support portions 25.

A current detector 31 is provided for detecting a current flowing through the wire 27. In the present embodiment,
As the current detector 31, a non-contact type current detector that detects the value of the current flowing through the wire 27 from the strength of the magnetic field generated around the wire based on the current flowing through the wire 27 is used. Specifically, in the present embodiment, an annular ring made of a conductive material and surrounding the wire 27 is used as the non-contact type current detector in order to detect the strength of a magnetic field formed around the wire 27. ing. This annular ring is located approximately halfway between the two supports 26 as shown,
So that the wire 27 passes through substantially the center of the annular ring,
Preferably, it is fixed to the housing 14 or the circuit box 28. The current detector 31 is also connected to an arithmetic circuit 32 that calculates a current value based on an output signal of the current detector 31. In the present embodiment, the arithmetic circuit 32 is fixedly supported by the circuit box 28, but may be provided in an external circuit connected to the output unit 33 of the circuit box 28.

According to the torque detecting device 10 having the above configuration, the torque applied to the input shaft 12 is transmitted to the output shaft 13 via the input coupling 16, the torsion bar 18, and the output coupling 17. You. The torsion bar 18 twists according to the torque applied to the torsion bar 18. Thereby, FIG. 3 (b-1), (b-
As shown in 2), one support portion 26 is connected to the other support portion 2.
6 is rotated about a central axis 11. In addition, the distance between the two support portions 26 increases due to the relative movement of the support portions 26. As a result, the tension of the wire portion (electric wire portion) 27a whose both ends are fixed between the support portions 26 increases, and the wire portion 27a is distorted. This distortion causes a change in the resistance of the wire 27 and further in the current flowing through the wire 27, and the change in the current is detected by the current detector 31. The arithmetic circuit 32 calculates a change in resistance from a change in current and calculates a torque according to the principle described below.

The method of calculating the torque will be described. Now, let the radial distance between the central axis 11 and the wire portion 27a be (r),
The initial length of the wire portion stretched between the support portions 26 is (2
L), assuming that the torsion angle of the other support portion 26 with respect to the one support portion 26 is (2θ), the length (2L ′) of the wire portion after deformation is given by the following equation (1).

Change in current flowing through wire 27 (ΔI)
Sets the initial resistance value of the wire 27 to (R ₀), Change in resistance
From (ΔR) and the power supply voltage (V) by the following equation (2).
available. The amount of change in current (ΔI) is determined based on torque detection.
It is used as an index indicating the sensitivity of the device 10.Therefore, the change in the current detected by the current detector 31 is
From the equation (2), the amount of change in resistance (ΔR) is obtained.
You.

On the other hand, when the gauge factor of the wire is (G), (ΔR / R ₀ ) is given by the following equation (3).

By transforming equation (3) using equation (1), the following equation (4) is obtained.

From equation (4), the twist angle (θ) is given by the following equation (5).

On the other hand, the torsion angle (2θ) and the torque (T) are
It has a proportional relationship shown in the following equation (6). (K)
Is a constant, which is uniquely determined by the material and size of the torsion bar.

Therefore, the torque applied to the torsion bar is given by the following equation (7).

As is apparent from equation (2), when the power supply voltage (V) is increased, the current change (ΔI) is also increased. However, if the power supply voltage (V) is too large,
The current flowing through the wire 27 increases, and self-heating by Joule heat occurs. And the heat generation of the wire 27 is
This causes thermal expansion of the wire 27, which affects the calculated value. Therefore, the power supply voltage (V) needs to be set to such an extent that the wire 27 does not generate a large error in the calculation result due to heat generation. For example, assuming that the allowable maximum value of the heat generation amount is Pmax, the allowable power supply voltage Vmax of the present embodiment is given by the following equation (8).

As described above, according to the torque detecting device of the present embodiment, the torque acting on the torsion bar can be detected in a non-contact manner without using a mechanical contact component such as a brush. Therefore, there is no detection error due to wear and the like,
A highly reliable detection result can be obtained. Also, since the current detector and the wire do not require a high degree of assembly precision, the torque detector can be easily assembled.

[Second Embodiment] FIGS. 5 and 6 show a torque detector 102 according to a _second embodiment. The torque detector 10 ₂ is provided with an annular flange (support portion) 40a, and 40b as supporting portions near both ends of the torsion bar 18. The one annular flange 40a has through holes 41a and 41b at two places at a predetermined distance from the center axis 11 and at a predetermined angle in the circumferential direction. Similarly, the other annular flange 40b has the same distance from the central axis 11 and also has through holes 41b and 42b formed at two places at the same angle in the circumferential direction. The through holes 41a and 42a of the one annular flange 40a and the through holes 41b and 42b of the other annular flange 40b are arranged on respective planes passing through the central axis 11, and these through holes 41a, 41b and 42a are provided. Is the central axis 11
So that it is parallel to

The wire 43 is connected to one of the annular flanges 40a.
From one through hole 41a of the other annular flange 40b at a position facing the one through hole 41a, and from the other through hole 42b of the other annular flange 40b to the other The other through-hole 4 of one of the annular flanges 40a at a position facing the through-hole 42b
2a, and both ends are connected to the DC power supply 44. The wire portion 43a stretched between the through holes 41a and 41b and the wire portion 43b stretched between the through holes 42a and 42b are fixed by the adhesive 45 filled in the through hole, as in the first embodiment. Both wire portions 43a,
The same tension acts on 43b.

An electromagnetic shield 46 made of a magnetic shielding material is provided on the wire portion 43b stretched between the other through holes 42a and 42b. However, the remaining one wire portion 43a is not covered with the electromagnetic shield.

The non-contact type current detector 47 is provided substantially at the center between the two annular flanges 40a and 40b.
An annular ring (conductive ring) surrounding the torsion bar 18 and the wire portions 43a, 43b, which is arranged substantially concentrically with the connector 8, is fixed to the circuit box 28 or the housing. The current detector 47 is provided with the arithmetic circuit 3
2 are connected.

The other structure is the same as that of the torque detecting device according to the first embodiment.

[0041] In the torque detecting device 10 _2, the strength of the magnetic field formed by current flowing through the wire portion 43a is detected by the current detector 47, corresponding to the signal (current value corresponding to the intensity of the magnetic field. ) Is output to the arithmetic circuit 32. Then, the arithmetic circuit 32 calculates the torque acting on the torsion bar 18 based on the input signal.
However, since the magnetic field formed by the current flowing through the other wire portion 43b is shielded by the electromagnetic shield 46, the current flowing through the wire portion 43b does not affect the detected value.

In the case of the second embodiment, the torsion bar 1
The amount of change (ΔI) of the current flowing through the wire 43 and the amount of change (ΔR) of the resistance of the wire 43 when the wire 8 is twisted are given by the following equation (9).

The amount of change in resistance (ΔR) is determined by the current detector 47.
Is obtained by substituting the change amount (ΔI) of the current detected in the equation (9) into the equation (9). Then, the torque applied to the torsion bar is obtained by substituting the resistance change (ΔR) into the equation (7). Note that, as is clear from the equations (9) and (2), the sensitivity of the second embodiment is the same as the sensitivity of the first embodiment.

Maximum allowable voltage Vmax of the second embodiment
Is given by the following equation (10).

As described above, the torque detecting device according to the present embodiment also employs no mechanical contact parts such as brushes and the like.
The torque acting on the torsion bar can be detected in a non-contact manner. Therefore, there is no detection error due to wear or the like, and a highly reliable detection result can be obtained. Also, since the current detector and the wire do not require a high degree of assembly precision, the torque detector can be easily assembled.

Third Embodiment FIG. 7 shows a torque detector according to a third embodiment. The torque detector 10 _3,
This is a modification of the torque detecting device according to the second embodiment, and is common in that a wire is arranged back and forth from one annular flange to another annular flange via the other annular flange. However, the torque detector 10 ₃ of the third embodiment, two annular flanges 51a, respectively one for 51b through hole 52a, and is formed 53b only. Further, the through hole 53a of one annular flange 51a and the through hole 53b of the other annular flange 51b are formed at different positions in the circumferential direction (see FIG. 8). Then, the wire 50 extends from one through hole 53a to the other through hole 53a.
b through the other through-hole 53b again to the one through-hole 5
3a, and the wire portions 50a, 50b are fixed with the same tension applied to the wire portions 50a, 50b by the adhesive 54 filled in the through holes 53a, 53b. Other 2
One wire portion 50a, 50b is connected in series to a DC power supply 55, and the other wire portion 50b is covered with an electromagnetic shield 56.

The other structure is the same as that of the torque detecting device according to the second embodiment.

In the third embodiment, the angle between the line 57 parallel to the central axis 11 and the wire portions 50a, 50b is (α), and the angle in the circumferential direction of the two through holes 53a, 53b is (β). Then, these two angles are calculated by the following equation (11).
Has a relationship represented by

[0049] Further, the wire portion 50a, the initial length 2L ₀ of 50b is given by the following equation (12).

Therefore, assuming that the torsion bar 18 is twisted by an angle (2θ) between the annular flanges 51a and 51b, the length 2 of the wire portions 50a and 50b after twisting is obtained.
L ′ is given by equation (13).

The amount of change in resistance of the wire 50 is given by the following equation (1).
4).

Therefore, the amount of change in resistance (ΔR) is obtained from the amount of change in current (ΔI) detected by the current detector 47, and this value and other known values [resistance value R ₀ , gauge number G, center The radial distance r between the shaft and the wire portion, the angle β,
From the initial length L of the wire portion, the torsion angle (θ) of the torsion bar and the torque are calculated.

In the case of the third embodiment, for example, FIG.
As shown in (1), when the other annular flange 51b is twisted in the direction of the arrow with respect to the one annular flange 51a, the tension of the wire portions 50a and 50b increases and the amount of change in resistance becomes a positive value. On the other hand, when twisted reversely, the wire portion 50
The tension of a and 50b decreases, and the amount of change in resistance becomes a negative value. Therefore, the direction in which the torque acts can be detected from the positive or negative of the resistance change amount.

Further, in the case of the third embodiment, the current change (ΔI) is given by equation (9).

Fourth Embodiment FIGS. 9 and 10 show a torque detecting device according to a fourth embodiment. This torque detecting device 1
0 ₄ is another modified example of the torque detection device according to Embodiment 2, in particular the arrangement of the wires are different. Specifically, each of the annular flanges 61a and 61b has four through holes 62a to 62d.
62d and 62a 'to 62d' are formed. Looking at the other annular flange 61a, the first and second through holes 62a, 62b are formed symmetrically with the second and third through holes 62c, 62d with respect to the cross section including the central axis 11. Similarly, the first and fourth through holes 62a and 62d are formed symmetrically with the second and third through holes 62b and 62c. Regarding the other annular flange 61b, the first to fourth through holes 62a 'to 62d' are formed similarly to the one annular flange 61a. Further, the through holes 62a to 62d of the one annular flange 61a and the through holes 62a 'to 62d' of the other annular flange 61b are symmetrical, that is, the first through holes 62a, 62a ', and the second through hole 62.
b, 62b ', the third through holes 62c, 62c', and the lines connecting the fourth through holes 62d, 62d '
And are arranged in parallel.

The wire 60 is connected to one of the annular flanges 61a.
From the first through hole 62a to the other annular flange 61b
Second through-hole 62b ′, and the other annular flange 6
1b, via the fourth through-hole 62d ', is disposed to the third through-hole 62c of one of the annular flanges 61a, and both ends are connected to the DC power supply 65. Further, another wire 60 ′ extends from the second through hole 62 b of the one annular flange 61 a to the first through hole 62 a ′ of the other annular flange 61 b and the third through hole of the other annular flange 61 b. One end of the annular flange 61a is arranged in the fourth through-hole 62d via 62c ', and both ends are connected to the DC power supply 65.

As shown in FIG. 9, one of the annular flanges 6
A wire portion 60a extending from the first through hole 62a of 1a to the second through hole 62b 'of the other flange 61b, and a first portion of the other annular flange 61b from the second through hole 62b of one annular flange 61a. The wire portions 60a 'extending to the through holes 62a' are arranged so as to intersect with the lines parallel to the central axis 11 so as to form a predetermined angle (α).

Similarly, as shown in FIG. 10, a wire portion 6 extending from the third through hole 62c 'of the other annular flange 61b to the fourth through hole 62d of the one flange 61a.
0b and the fourth through hole 62 of the other annular flange 61b.
d 'to the third through hole 62 of one of the annular flanges 61a
The wire portions 60b 'extending to the central axis 11
Are arranged so as to intersect with a line parallel to the predetermined angle (α). In addition, these two wire portions 60
b and 60b 'are covered with an electromagnetic shield 66.

FIG. 11 shows an equivalent circuit of the wires 60 and 60 'arranged as described above. As shown in this figure, the intersecting wire portions 60a, 60a 'and 60b,
60b 'are connected in parallel to the DC power supply 65, respectively.

The other structure is the same as that of the torque detecting devices according to the second and third embodiments.

The torque detecting device 10 according to the fourth embodiment₄
Now, the torque is not acting on the torsion bar 18.
In this state, the four wire portions 60a, 60b, 60a ', 6
0b 'are equal (R₁, R₂,
R₃, R₄= R₀), The other of the wire portions 60a and 60b
(I) flowing through the wire portions 60a 'and 60b'₁,
I ₂= V / 2R₀) Is also equal.

When a torque acts on the torsion bar 18 and the torsion bar 18 is twisted, the tension acting on one of the intersecting wire portions 60a, 60a 'and 60b, 60b' increases, The tension acting on the other wire portion is reduced. Therefore, 4
The resistance values (R ₁ ′, R ₂ ′, R ₃ ′, R ₄ ′) of the two wire portions 60 a, 60 b, 60 a ′, 60 b ′ are given by the following equations (15), (16).

The current (I) flowing through one wire portion 60a, 60b and the other wire portion 60a ', 60b'
₁ , I ₂ ) are given by the following equations (17) and (18).

Therefore, the current variation ΔI is given by the following equation (19).

Then, the amount of change in resistance (ΔR) is calculated from the amount of change in current (ΔI) detected by the current detector 67, and
Using the amount of change in the resistance, the torsion angle (θ) of the torsion bar and the torque are calculated. Equation (1)
As is clear from 9), the detection sensitivity of the torque is twice that of the first to third embodiments. Note that the maximum allowable voltage V
max is the same as in the second embodiment.

According to the fourth embodiment, as long as the tension of each wire portion 60a, 60b, 60a ', 60b' is set to be the same, the current flowing through each wire portion becomes constant. No adjustment is required. Further, when the other annular flange 61b is twisted in the direction of the arrow with respect to the one annular flange 61a, the tension of the wire portion 60a increases and the amount of change in resistance becomes a positive value. On the other hand, when twisted, on the other hand, the tension of the wire portion 60a decreases, and the amount of change in resistance becomes a negative value. Therefore, the direction in which the torque acts can be detected from the positive or negative of the resistance change amount.

[Embodiment 5] FIG. 12 shows Embodiment 5 of the present invention.
1 shows a torque detecting device of the present invention. This torque detecting device 10
₅ is another modified example of the torque detecting device according to the second embodiment, in which one annular flange 71a and the other annular flange 7 are provided.
Eight through-holes 72a and 72b are formed in 1b so as to face each other. The wire 70 has four wire portions 70a to 70d stretched in parallel from one annular flange 71a to the other annular flange 71b in parallel with the central axis 11, and these four wire portions 70a to 70d They are connected on the side of the annular flange 71b. Similarly,
Four wire portions 70a 'to 70 branched from the connection portion
d ′ is stretched in parallel from the other annular flange 71b toward the one annular flange 71a in parallel with the central axis 11. Also, these four wire portions 70a 'to 70a
d ′ is covered with the electromagnetic shield 76. On the one annular flange 71a side, the former four wire portions 70a to 70d and the latter four wire portions 70a 'to
70 d ′ is connected to both poles of the DC power supply 75. FIG. 13 shows an equivalent circuit of the wire portion thus arranged.

Therefore, in the present embodiment, the currents I ₁ , I ₂ ,
The sum (I) of I ₃ and I ₄ is detected by the current detector 77. See the following equation (20).

When torque is applied to the torsion bar 18 to cause torsion, resistance changes in the same direction appear in all four wire portions 70a to 70d. At this time, the sum of the currents flowing through the four wire portions 70a to 70d (I ')
Is given by equation (21).

Therefore, the current change (ΔI) is given by equation (22). As is apparent from the equation (22), the torque detection device according to the fourth embodiment can obtain twice the current sensitivity as that of the fourth embodiment.

The two annular flanges 71a, 71b
The current change amount (ΔI) when a plurality of (N) wire portions are arranged in parallel is given by the general formula (23), and the current sensitivity increases according to the number of wire portions arranged in parallel. .

In the present embodiment, a plurality of wire portions are arranged in parallel with the central axis. However, as in the fourth embodiment, they may be arranged non-parallel to the central axis. In this case, since the current flowing through the wire portion increases or decreases according to the direction of the torque, the direction in which the torque acts can also be detected.

Further, as in the fourth embodiment, if a plurality of wire portions having different current flowing directions are arranged so as to cross each other, the sensitivity is further improved, and the forward and return paths in a state where no torque is applied. , The difference (offset) in the current flowing through the current can be easily removed.

[Sixth Embodiment] Depending on the mounting location of the torque detecting device, there is a possibility that a current may flow through the torsion bar due to external electric noise or the like. At this time, if the current detector surrounds the torsion bar as shown in Embodiments 2 to 5, the current detector also detects the current (noise current) flowing through the torsion bar, and an error may occur in the detection result. . Therefore, as shown in FIG. 14, it is preferable that the torsion bar portion 18a between the wire support portion and the annular flange is also covered with the similar electromagnetic shield 81. According to the sixth embodiment, the current is not detected by the torsion bar 18 due to external electric noise or the like.
Reliable detection results are obtained. In the description of the present embodiment and other embodiments described below, the reference numerals used in the description of the above-described second embodiment are used, and new reference numerals are assigned only to newly added configurations. ing.

[Seventh Embodiment] In the sixth embodiment, the torsion bar is surrounded by an electromagnetic shield in order to eliminate a detection error due to a current flowing through the torsion bar 18, but as shown in FIG. A part of the torsion bar 18 may be constituted by an electrical insulator 82 continuous in the circumferential direction to prevent the current from flowing through the torsion bar 18. However, in the case of the present embodiment, in order to keep the torsional rigidity of the torsion bar 18 uniform at all places, the electric insulator 82 is used.
Should select a material having the same torsional rigidity as the torsion bar 18.

[Embodiment 8] In the above embodiment,
Although a DC power supply is used as the power supply, an AC power supply (power supply device) may be used instead. Embodiment 8 shown in FIGS. 16 to 18 is an example in which an AC power supply is used as a power supply.
A primary coil 84 connected to 3 is arranged. A secondary coil 85 is arranged on the torsion bar 18 adjacent to the primary coil 84 (in the present embodiment, inside the primary coil 84), and both ends of the secondary coil 85 are connected to the wire 43. I have. In order to increase the magnetic flux density, the primary coil 84 and the secondary coil 85 are preferably wound around annular iron cores 87 and 88, respectively. In the case of this embodiment, the primary coil 84
Is applied to the primary coil 8 (current: I ₁ ).
4, an alternating magnetic field is formed. Then, an alternating current is induced in the secondary coil 85 by this alternating magnetic field, and
Is applied to At this time, the current (I
₂ ) is given by the following equation (24). In equation (24), (I ₁ ) is the current flowing through the primary coil, (ω) is the angular frequency of the current I ₁ , (M) is the mutual inductance between the primary coil and the secondary coil, and (L ₂ ) is The self-inductance of the secondary coil, (R) is the resistance of the wire.

In the case of this embodiment, the torsion bar 18
When a torque acts on the torsion bar, the resistance of the wire changes, and the amplitude of the alternating current changes. The current detector 47 detects a change in the amplitude of the alternating current, and the calculation circuit 32 calculates the torque based on the change in the amplitude.

Further, according to the present embodiment, it is not necessary to connect wires directly to the power source, so that the torsion bar 1 is not required.
Wiring can be performed without considering the amount of twist of 8, and the degree of freedom of wiring increases.

[Embodiment 9] In the embodiment 8, AC is applied to the wire. However, an AC current induced in the secondary coil may be converted to DC and applied to the wire. In this case, as shown in FIG. 19, the alternating current induced in the secondary coil 85 is rectified into direct current by the rectifier circuit 90,
To generate a predetermined constant voltage (Vdc),
A DC voltage adjusted to a predetermined voltage (Vb) is applied to the wire 43 via the wire.

[Embodiment 10] When an alternating current is applied to a wire, the alternating current (voltage Vac) induced in the secondary coil 85 is adjusted to a predetermined voltage (Vb) by a buffer circuit 92 as shown in FIG. Then, the adjusted AC voltage may be applied to the wire 43. In this case, as shown in the figure, a part of the current induced in the secondary coil 85 is converted to DC by the rectifier circuit 90, adjusted to a predetermined DC voltage by the smoothing circuit 91, and the adjusted DC voltage is buffered. The driving voltage of the circuit 92 may be used.

In the embodiments after the second embodiment, an annular flange is used as a supporting portion for supporting a wire, but this annular flange can be replaced with a plurality of supporting portions corresponding to each through hole. .

In the above description, a non-contact type current detector is used as the current detector, but may be replaced with an ammeter directly connected to a power supply.

[0083]

As is clear from the above description, according to the torque detecting device of the present invention, the torque acting on the torsion bar can be detected in a non-contact manner without using a mechanical contact component such as a brush. Therefore, there is no detection error due to wear or the like, and a highly reliable detection result can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram relating to electronic control power steering control of a vehicle.

FIG. 2 is a partial perspective view of the torque detection device according to the first embodiment.

FIG. 3 is a diagram showing a state of a wire stretched between two support portions in the torque detection device according to the first embodiment.

FIG. 4 is a cross-sectional view of the torque detection device according to the first embodiment.

FIG. 5 is a partial perspective view of the torque detection device according to the second embodiment.

FIG. 6 is a sectional view of a torque detection device according to a second embodiment.

FIG. 7 is a partial perspective view of a torque detection device according to a third embodiment.

FIG. 8 is a diagram showing positions of through holes formed in two annular flanges in the torque detection device according to the third embodiment.

FIG. 9 is a partial perspective view of a torque detection device according to a fourth embodiment.

FIG. 10 is a partial perspective view of a torque detection device according to a fourth embodiment.

FIG. 11 is an equivalent circuit diagram of the torque detection device according to the fourth embodiment.

FIG. 12 is a partial perspective view of a torque detection device according to a fifth embodiment.

FIG. 13 is an equivalent circuit diagram of the torque detection device according to the fifth embodiment.

FIG. 14 is a partial perspective view of a torque detection device according to a sixth embodiment.

FIG. 15 is a partial perspective view of a torque detection device according to a seventh embodiment.

FIG. 16 is a partial perspective view of a torque detection device according to an eighth embodiment.

FIG. 17 is a sectional view of a torque detector according to an eighth embodiment.

FIG. 18 is a power supply circuit diagram of the torque detection device according to the eighth embodiment.

FIG. 19 is a power supply circuit diagram according to another embodiment (Embodiment 9).

FIG. 20 is a power supply circuit diagram according to another embodiment (Embodiment 10).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Torque detection device, 11 Central axis, 18 Torsion bar, 25 Support part, 26 Through-hole, 27
Wire, 27a wire part, 29 DC power supply,
31 current detector, 32 arithmetic circuit.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 3D033 CA28

Claims (14)

[Claims] 1. A device for detecting a torque acting on a rod-like body, wherein the torque detector is fixed to the rod-like body at a distance in a longitudinal direction thereof.
A support wire, a strain wire having a wire portion stretched between the two support portions, and having a predetermined relationship between strain and electrical resistance; and a power supply device for applying a predetermined voltage to the strain wire; A current detector for detecting a current flowing through the strain wire; 2. A device for detecting a torque acting on a rod-like body, comprising: a power supply unit; and a power supply unit fixed to the rod-like body at a distance in a longitudinal direction thereof.
And two electric wire portions stretched between the two support portions, and one of the electric wire portions and the other electric wire portion are connected in series to the power supply device. A torque detection device comprising: a strain wire having a relationship; and a current detector for detecting a current flowing through the strain wire. 3. A device for detecting torque acting on a rod, comprising: a power supply unit; and a power supply unit fixed to the rod at a distance in a longitudinal direction thereof.
One and two wires connected in parallel to the power supply device, and having a predetermined strain and electrical resistance. A torque detection device comprising: a strain wire having a relationship; and a current detector for detecting a current flowing through the strain wire. 4. The torque detecting device according to claim 3, wherein one or the other electric wire portion connected in series is covered with a magnetic shielding member. 5. The torque detecting device according to claim 1, wherein the electric wire portion is stretched in parallel to a long axis of the rod. 6. The torque detecting device according to claim 1, wherein the electric wire portion is stretched non-parallel to a long axis of the rod. 7. The torque detecting device according to claim 3, wherein the two electric wire portions connected in parallel are arranged so as to cross each other around the rod. 8. The current detector according to claim 1, wherein the current detector is a non-contact current detector that detects the magnitude of the current based on a change in a magnetic field caused by a change in a current flowing through the electric wire. Item 8. The torque detecting device according to any one of Items 1 to 7. 9. The non-contact type current detector has an annular ring made of a conductive material, and the annular ring is arranged so as to surround the electric wire portion.
3. The torque detecting device according to 1. 10. The non-contact type current detector has an annular ring made of a conductive material, and the annular ring is arranged so as to surround the electric wire portion and the rod. 9. The torque detection device according to 8. 11. The torque detecting device according to claim 1, wherein the rod is covered with a magnetic shielding member. 12. The torque according to claim 1, wherein the rod-shaped member is provided with an electric insulator for preventing a current from flowing between the two support portions. Detection device. 13. The power supply device is provided with a primary coil provided on a fixing portion supporting the rod, a magnetic coil connected to the primary coil provided on the rod and connected to the strain wire. The torque detecting device according to claim 1, further comprising a secondary coil, and an AC source that applies an AC to the primary coil. 14. The torque detecting device according to claim 1, further comprising an arithmetic circuit for calculating a torque applied to the rod from the output of the current detector.